1. Field of the Invention
The present invention relates to ammunition and particularly to cartridge cases intended to receive a charge of pellets. More specifically, this invention is directed to the manufacture of cartridge cases, shotgun shell cases for example, having a plastic side wall and a metal head. Accordingly, the general objects of the present invention are to provide novel and improved articles and methods of such character.
2. Description of the Prior Art
There have, in recent years, been numerous attempts to produce cartridge cases of the type used by sportsmen; i.e., shotgun shells; entirely of plastic material. Attempts to produce cartridge cases comprised entirely of plastic have been unsuccessful and it has been found preferable to reinforce such cases with a metal head or cap as is normal practice with conventional cardboard cartridge cases. The inclusion of a metal head avoids the risk that the plastic material, defining the sidewall of the cartridge, will break when the shot charge is expelled therefrom. Additionally, the metal head is necessary to eliminate expansion of the plastic portions of the case subsequent to firing of the ammunition. Such expansion, if permitted, will cause the casing to become jammed in the bore of the weapon and render extraction thereof exceedingly awkward and difficult.
The manufacture of plastic cartridge cases having a metal head has been found to be a relatively complicated operation. Substantial difficulty had been encountered in securely affixing the metal head to the plastic case body and, in numerous cartridges, it has been observed that the head and plastic case body separated during firing of the ammunition whereby the normal extraction of the cartridge case from the firearm could not be accomplished. The U.S. Pat. No. 3,565,008 describes a prior art method for securing a metal head to a cartridge case body comprised of plastic material. The technique of U.S. Pat. No. 3,565,008 is complex and thus time consuming and expensive since two separate sets of tools are required. The first set of tools is employed for forming the rough shape of the metal head and the second set of tools produces the finished head simultaneously with joining of the head to the cylindrical plastic case body. In order that the metal head be perfectly fixed to the plastic case body, it is essential for the second set of tools to be very precise in operation. Thus, if the cylindrical part of the metal head is not properly formed and/or if the rim on the head is inadequately defined, there will be insufficient deformation of the plastic case body during the assembly procedure to insure firm attachment of the metal head to the plastic body.